Idiopathic pulmonary fibrosis (IPF) is a chronic and often fatal pulmonary disorder. Conventional treatment with immunosuppressive therapy in IPF has been disappointing. The pathology of IPF demonstrates features of dysregulated/abnormal repair with exaggerated angiogenesis, fibroproliferation, and deposition of extracellular matrix, leading to progressive fibrosis and loss of lung function. The elucidation of mediators which orchestrate this aberrant tissue repair, as well as their longitudinal expression, will allow the development of novel interventions to treat this disorder. Interleukin-8 (IL-8), a member of the CXC chemokine family, has recently been shown to be a potent mediator of angiogenesis. In contrast, platelet factor 4 (PF4) and interferon gamma-inducible protein 10 (IP-10), related members of the CXC chemokine family, are angiostatic. We hypothesize that angiogenesis is an important process that contributes to the pathogenesis of pulmonary fibrosis, and that this neovascular response is dependent upon an imbalance of angiogenic vs angiostatic CXC chemokines. This paradigm predicts that the biological balance in the expression of these CXC chemokines dictates that angiogenesis in association with fibroproliferation either regresses or progresses to end-stage pulmonary fibrosis. In this proposal, we will focus on the role of angiogenic and angiostatic CXC chemokines and establish whether a biological imbalance in their expression favors the progression of pulmonary fibrosis. Our experimental strategy will address the following questions: l) Do specific cytokine networks exist during pulmonary fibrosis that shifts the biological balance in favor of angiogenic CXC chemokines? 2) Can gene transfer strategies induce a cytokine network that shifts the biological balance in favor of angiostatic CXC chemokines and reduce pulmonary fibrosis? 3) What is the cellular and molecular mechanism(s) that accounts for the disparity of IPF and control fibroblast production of angiogenic and angiostatic CXC chemokines? 4) Can angiostatic CXC chemokine gene transfer to human IPF pulmonary fibroblasts alter their phenotype and reestablish normal pulmonary fibroblast-like angiogenic activity. 5) Does an imbalance in angiogenic and angiostatic CXC chemokines, at baseline or in a temporal manner, correlate with various parameters of disease activity or response to therapy in IPF patients? BAL, lung tissue, and plasma will be obtained from IPF patients and control subjects. Pulmonary fibroblasts will be isolated from either IPF or control lung tissue. Bleomycin-induced murine lung fibrosis will serve as our in vivo experimental model of pulmonary fibrosis. Techniques employed in this application will include: Northern blot (or RT-PCR) and in situ hybridization analysis; cellular transfection; adenovirus-mediated CXC chemokine gene transfer, immunohistochemistry and ELISAs to determine cytokine production; bioassays for angiogenic activity; morphometric and FACS analyses of neovascularization and inflammation, in vivo depletion of CXC chemokines by passive immunization with neutralizing antibodies. The elucidation of the biology of angiogenic and angiostatic CXC chemokines in lPF will permit the development of novel and targeted therapy aimed specifically at attenuating pulmonary fibrosis.